Cardiovascular lesions in 5 patients with the Hurler syndrome involved the coronary arteries, the 4 cardiac valves, the mural endocardium, the myocardium and the aorta. These sites contained large, clear cells with deposits of acid mucopolysaccharides; in addition, cardiac muscle cells and smooth muscle cells contained deposits of glycolipid material. These changes led to valvular deformities and to extremely severe narrowing of the coronary arteries. BIBLIOGRAPHIC REFERENCES: Renteria, V.G., Ferrans, V.J., and Roberts, W.C.: The heart in the Hurler syndrome. Gross, histologic and ultrastructural observations in five necropsy cases. Am J Cardiol 38: 487-501, 1976.